Friction control device

ABSTRACT

A control device selectively applies friction to a control mechanism adapted for feeding lathe knives in a grinding machine, whereby overrun of the mechanism or inaccuracy in its operation is substantially prevented. The control device is selectively locked out of its friction-applying position to allow rapid insertion and removal of knives.

O Umted States Patent 1 1 3,733,733 Miller et a]. 1 May 22, 1973 541FRICTION CONTROL DEVICE 586,745 7/1897 Pierce et al ..188/83 7 1,199,6729/1916 Dick 51/249 X [76] Inventors: Robert C. Miller, 3350 Greenhill 1355 957 4/1932 Gomcky "51/34 5 1 Road, Junction City, Oreg. 97448;2,149,774 3/1939 Ingleman ..5l/34E Gordon E. Stoddard, 2677 Friendly vstreet, Eugene, 0 97401 Primary Examiner-Othell M. Simpson [22] File 0 t20 1.971 Attorney-Stephen W. Blore et al.

211 Appl. No.: 190,786 [57] ABSTRACT A control device selectivelyapplies friction to a con- 52 US. Cl. ..51/34 E, 188/83 [51] Int. Cl...B24b 7/00, B24b 9/00 or inaccuracy in its operation substantially [58]Field Search 34 1653 prevented. The control device is selectively lockedout 51/32, 39; 188/ 83 of its friction-applying position to allow rapidinsertion and removal of knives. [156] 1 References Cited v 10 Claims, 4Drawing Figures UNITED STATES PATENTS PATENIE mama ROBERT C. MILLERGORDAN E. STODDARD IN VENTORS.

BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS FRICTION CONTROL DEVICEBACKGROUND OF THE INVENTION The present invention relates to a frictioncontrol device for a machine tool feeding mechanism and particularly toa friction control device applicable for maintaining accuracy of feed.

In a type of grinding machine commonly employed for grinding large latheknives used in plywood veneer peeling lathes, a feeding mechanism movesa knife being ground progressively closer to a grinding wheel after eachpass of the grinding wheel along the knife. The feed is, of course,accurately predetermined whereby the desired amount of metal is groundaway on each pass, the automatic feed mechanism generally comprisingaratchet device for moving the knife blade closer to the grinding wheelby a predetermined amount for each operation of the ratchet device.Unfortunately, machine operation and inertia of components is such thatthe feed mechanism tends to overshoot. Thus a ratchet pawl is apt tourge a feed wheel farther than just the amount of pawl movement. It is,of course, possible to provide excessive friction in the operation ofthe feed mechanism by maintaining tight feed screw tolerances and/orapplying axial pressure to the feed screw such that no overrun or thelike will ordinarily take place. However, application of friction inthis way hampers the manual operation of the feed device for insertingor replacing knives to be ground. Thus, a feed wheel associated with thefeed mechanism may typically have to be rotated by as many as 65 to 70revolutions for moving the machine bed plate to a position where a newblade can be inserted. Therefore, friction control is not apt to beemployed inasmuch as the machine output is correspondingly reduced whenaddi tional time is required in changing knives. In the usual case, themachine operator closely monitors the feed in order that inaccuracy oroverrun of the feed can be corrected after each pass of the grindingmechanism, and then the operator changes blades.

SUMMARY OF THE INVENTION According to the present invention, an improvedfriction control device comprises a bracket frame adapted to be securedto the main frame of a grinding machine or the like, this bracket frameslidably supporting a shaft carrying an arcuate shoe positioned adjacentthe periphery of a feed wheel or control wheel. The shoe is providedwith a frictional surface for normally contacting the periphery of thefeed wheel and preventing overrun of the automatic feed mechanism. Thefriction control device is further provided with a means for rapidlyupraising and locking the aforementioned shoe out of contact with thefeed wheel whereby the machine operator can rapidly and convenientlyremove the frictional force and rapidly transfer the machine bed plateinto and out of position, as when changing knives. The mechanism thusprovides for accurate and versatile machine operation. Moreover, thefriction control device is economical in constructionand easily mountedupon the machine without requiring extensive alteration or evendisassembly of the machine.

It is accordingly an object of the present invention to provide animproved friction control device for accurately controlling the feed ofa machine tool.

It is another object of the present invention to provide an improvedfriction control device for a machine tool, which device is adaptablefor normally enhancing the accuracy of'feed operation of the machinetool, while being readily controllable to facilitate alternative rapidfeed operation.

It is another object of the present invention to provide an improvedfriction control device for a machine tool, which device is economicalin operation and readily and easily attached to such tool withoutrequiring remanufacture or even disassembly thereof.

It is a further object of the present invention to provide an improvedfriction control device for a ratchet control feed mechanism, whichdevice is adapted for preventing overrun of such mechanism as well asbacklash in cooperating parts.

The subject matter which we regard as our invention is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. The invention, however, both as to organization andmethod of operation, together with further advantages and objectsthereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawings whereinlike reference characters refer to like elements.

DRAWINGS FIG. 1 is a plan view of a machine for grinding chipper andlathe knives or the like, such machine including a new and improvedfriction control device;

FIG. 2 is an enlarged vertical cross section, partially broken away,taken through the automatic feed mechanism of the FIG. 1 machine at line2-2 in FIG. I, more clearly illustrating the aforementioned frictioncontrol device;

FIG. 3 is an end view of the automatic feed mechanism of the FIG. 1machine having the said friction control device mounted thereon; and

FIG. 4 is a cross-sectional view taken at 4-4 in FIG. 2 through thetension adjustment portion of the aforementioned friction controldevice.

DETAILED DESCRIPTION The present invention is effective in combinationwith a grinding machine of the type employed for grinding veneer peelinglathe knives, for improving the operation of such machine. The generalstructure of the grinding machine is known, an example being of the typemanufactured by Capitol Machine Company, Inc., Indianapolis, Indiana.

The grinding machine It) includes automatic work feeding mechanism 12slidably mounted upon a guideway 16 of a main frame 14, such feedingmechanism specifically including a slide 22 movable along the guidewayand having a threaded connection with a feed screw 17. The right-handend of the grinding machine is provided with a similar mechanism (notshown) operated via bevel gears 89 and shaft 114. Inward feed of theknife to be sharpened is accomplished by rotation of feed wheel 62,either automatically or by means of hand wheel 71 connected thereto,which turns the feed screw 17. A bed plate 20 connects slides 22, ateach end of the machine, and such bed plate supports knife clamps 24 forsecuring a knife 26 to the top surface 28 of the bed plate in the properposition to be ground by a grinding wheel 30 carried on the end of shaft32 of motor 34. The motor 34 is secured to a carriage 36 which moveslongitudinally along supports 38, forming part of the main frame 14 ofthe grinding machine. The

carriage 36 is fed leftwardly and rightwardly by means of a feed screw40 rotated with a reversible motor 42 via belt drive 44. The grindingwheel 30 moves back and forth across the face of the knife 26 sharpeningthe same at the desired angle.

On the completion of each cycle of longitudinal movement, the carriage36 contacts an upstanding rod 46 of an advancing means 48, moving therod to the left in FIG 1 for rotating connecting rod 50. Affixed to oneend of rod 50 is a vertical bar 52 from which a pawl 54 is pivoted at56. End 58 of the pawl 54 engages ratchet teeth 60 formed on an outerperiphery of feed wheel 62 for rotating feed screw 17 and advancing bedplate on guideways 16 a predetermined distance toward grinding wheel 30.Therefore, upon the next longitudinal movement of carriage 36, thegrinding wheel 30 will grind off a few more thousandths of an inch ofmaterial from the knife.

According to the present invention, friction control device 70 causesthe feed mechanism to maintain an even, calibrated grinding feed. Thisdevice includes an angularly bent bracket frame 72 comprising a steelbar having its lower vertical portion attached by bolts 74 to the mainframe 14 of the grinding machine, and specifically by way of a brace 73.The upper angular portion 82 of the bracket frame is provided with adepending flat apron or shield 76 disposed at right angles to the bar.This apron keeps arcuately shaped shoe 84 of the friction control devicein general alignment with smooth peripheral surface 88 of feed wheel 62which is located adjacent the aforementioned teeth 60. Thus, the shoe 84is prevented from being turned crossways of the control wheel orinterfering with the operation of the tooth and ratchet mechanism. Theapron also aids in preventing injury to the operator by acting as aforward safety guard in front of the ratchet and friction mechanisms.The forward edge of the apron is adjacent the shoe, and is also suitablyarcuate in contour.

A shaft 78 extends through a bushing 80 welded into an aperture in theupper portion 82 of the bracket frame 72 (see FIGS. 2 and 4), and weldedto the lower end of the shaft 78 is the aforementioned arcuately shapedshoe 84, having a lining 86 suitably in the form of rubber-faced cottonfabric belting secured thereto with contact cement. A face of thislining 86 normally contacts smooth cylindrical surface 88 of feed wheel62 (to the right of teeth 60 in FIG. 3). It will be seen that shaft 78and apron 76 are substantially parallel. Elements 86 and 88 have thesame radius.

The upper end of the shaft 78 is threaded at 90 to receive jam nut 92,and a cap nut 94. A locking collet 96 is movable on the shaft betweenbushing 80 and jam nut 92, collet 96 being provided with an upperknurled radial flange 104. As can be seen in FIG. 2, the locking collet96 has a pair of V-shaped male dovetail portions or detent cams 98 onits lower edge, normally received within matching V-shaped femaledovetail portions 100 along the top edge of bushing 80. The dovetailportions are spaced by approximately 180 around shaft 78. A spring 102is positioned on shaft 78 between the top of the shoe 84 and the bottomof the bushing 80 and with the collet 96 in the position illustrated aconstant pressure can be maintained between the lining 86 and smoothcylindrical surface 88 of wheel 62. When it is desired to release thispressure, the knurled flange 104 of the collet 36 is manually upraisedand rotated by 90 for raising the male dovetail or detent cam 98 up outof the matching female dovetail 100 and onto cylindrical edge portion106. The shoe 84 is raised thereby above the cylindrical periphery ofwheel 62 and is effectively locked in this position whereby wheel 62 mayturn freely.

With the shoe 84 in its lower friction-applying position, the automaticfeeding mechanism, including such mechanism at each end of the grindingmachine, is constrained to provide a smooth and accurate feed after eachpass of the grinding wheel 30. The pawl 54 advances the feed wheel 62the desired amount, corresponding to the pawl movement, without overrunof the control wheel, that is without free wheeling of the control wheelto a further angular position. Moreover, backlash in the mechanismincluding the feed screw 17 and slide 22 as well as bevel gears 99 andsubsequent mechanism is substantially eliminated. Therefore, an accurateand uniform preset feed can be maintained for the ratchet mechanism.

However, when extensive rotation of feed wheel 62 is desired as in thecase of outward movement of bed plate 20 for removing a knife and inwardmovement of the bed plate for carrying a knife to the sharpeningposition, the friction control device is upraised by upraising theknurled flange 104 and rotating the same by approximately The shoe 84now releases the feed wheel 62 to a free wheeling condition whereby amachine operator can rapidly rotate the feed wheel (by means of handwheel 71) and move the bed plate in and out. Thus, accurate automaticfeed of the grinding machine is maintained by the present invention asdesired, but the friction control device is readily and easily releasedas required for rapid operation of the mechanism.

Consequently, the friction control device according to the presentinvention allows maximum utilization of operator time. The operator neednot constantly watch the automatic feed mechanism in order to insure thecorrect feed is accomplished after each pass of the grinding wheel.Therefore, the operator is freed for other duties when a knife is beingground. Furthermore, when a knife is ground and it is desired to removethe same and place a second knife in the machine for grinding, theoperator can rapidly move the knifecarrying bed plate in and out withouthaving to urge the feed mechanism slowly against a permanentantibacklash or friction device.

While we have shown and described the preferred embodiment of ourinvention, it will be apparent to those skilled in the art that manychanges and modifications may be made without departing from ourinvention in its broader aspects. We therefore intend the appendedclaims to cover all such changes and modifications as fall within thetrue spirit and scope of our invention.

We claim:

1. in a feed mechanism for a machine tool having a rotatable feed wheelfor bringing about relative motion between the work and machining means,a friction control device comprising:

bracket frame means adapted to be secured to the frame of said machinetool;

an arcuate shoe positioned by said bracket frame means proximate theperiphery of said feed wheel, said shoe having a lining material forcontacting the periphery of said feed wheel in frictional relation;

means for urging said shoe toward said feed wheel to produce frictionalengagement therewith;

and means for selectively securing said shoe in upraised positionrelative to said feed wheel for freeing said feed wheel from frictionalengagement.

2. The device according to claim 1 wherein said means for selectivelysecuring said shoe comprises cooperative cam members, and means foroperating one of said cam members for selectively upraising said shoerelative to said feed wheel.

3. The device according to claim 2 including a shaft secured to saidshoe, said shaft being slidably supported by said bracket frame meansfor movement toward and away from said feed wheel, said cam memberscomprising cylindrical cam members disposed substantially coaxially withrespect to said shaft, one of said cam members being secured to saidbracket frame means and the other being rotatable for moving said shaftand the shoe carried thereby in a direction longitudinal of said shaft.

4. In a grinding machine including a main frame and grinding means, andhaving a rotatable feed wheel adapted to bring about relative motionbetween work and the said grinding, means in response to cyclicalgrinding operation, wherein relative movement also occurs between saidgrinding means and the work in a direction therealong, a frictioncontrol device comprising:

a bracket frame adapted to be secured to the main frame of said grindingmachine, said bracket frame having an aperture;

a shaft extending through said aperture in said bracket frame andslidable with respect thereto,

said shaft carrying an arcuate shoe positioned by said bracket frameproximate the periphery of said feedwheel, said shoe carrying liningmaterial for contacting the periphery of said feedwheel in frictionalrelation;

a spring carried by said shaft between said bracket frame and said shoefor biasing said shoe toward said feedwheel to exert force between saidlining and said feedwheel;

and means carried by said shaft on the reverse side of said bracketframe from said spring for selectively locking said shoe in an upraisedposition relative to said feedwheel and freeing said feedwheel fromfrictional engagement.

5. The device according to claim 4 wherein said means for selectivelylocking said shoe in an upraised position comprises cooperatingcylindrical cam members respectively attached to said bracket frame androtatable on said shaft while being longitudinally engageable therewith,said cam members having a first cooperating position providing theclosest axial spacing thereof along said shaft adapting said shaft tocarry the arcuate shoe lining material into frictional contact with thesaid feedwheel, and an upraised level position for locating the arcuateshoe lining material out of contact with the periphery of saidfeedwheel.

6. The device according to claim 5 wherein said cam members respectivelycomprise a bushing attached to the said bracket frame and positionedaround the aperture thereof, and a collet rotatable on said shaft, saidcollet being provided with a knurled radial flange means for rotatingthe same, one of said cam members having at least one female dovetail orV-shaped slot adjacent the other cam member, the second cam memberhaving at least one matching V-shaped male dovetail portion adapted tobe received within the female dovetail portion and alternativelyupraisable by means of said radial flange for positioning said dovetailportions out of registry, with the male dovetail portion resting uponthe upper edge of the opposite cam member.

7. The device according to claim 6 further including a cap nut and a jamnut secured against one another on an upper threaded portion of saidshaft on the remote side of said cam members from said bracket frame.

8. The device according to claim 4 wherein said bracket frame comprisesan angular steel member having a lower portion thereof which is adaptedto be secured to the main frame, and carrying said arcuate shoe by anupper portion thereof angularly related to the lower portion.

9. The device according to claim 4 further including an apron extendingfrom said bracket frame in substantially parallel relation to the saidshaft as well as in substantially perpendicular relation to said bracketframe, said apron extending to a position adjacent said arcuate shoe.

10. The device according to claim 9 wherein said apron has an arcuateedge adjacent said arcuate shoe, said arcuate edge having a forwardcontour substantially matching that of the arcuate shoe.

. ll =k l =l= 1

1. In a feed mechanism for a machine tool having a rotatable feed wheelfor bringing about relative motion between the work and machining means,a friction control device comprising: bracket frame means adapted to besecured to the frame of said machine tool; an arcuate shoe positioned bysaid bracket frame means proximate the periphery of said feed wheel,said shoe having a lining material for contacting the periphery of saidfeed wheel in frictional relation; means for urging said shoe towardsaid feed wheel to produce frictional engagement therewith; and meansfor selectively securing said shoe in upraised position relative to saidfeed wheel for freeing said feed wheel from frictional engagement. 2.The device according to claim 1 wherein said means for selectivelysecuring said shoe comprises cooperative cam members, and means foroperating one of said cam members for selectively upraising said shoerelative to said feed wheel.
 3. The device according to claim 2including a shaft secured to said shoe, said shaft being slidablysupported by said bracket frame means for movement toward and away fromsaid feed wheel, said cam members comprising cylindrical cam membersdisposed substantially coaxially with respect to said shaft, one of saidcam members being secured to said bracket frame means and the otherbeing rotatable for moving said shaft and the shoe carried thereby in adirection longitudinal of said shaft.
 4. In a grinding machine includinga main frame and grinding means, and having a rotatable feed wheeladapted to bring about relative motion between work and the saidgrinding means in response to cyclical grinding operation, whereinrelative movement also occurs between said grinding means and the workin a direction therealong, a friction control device comprising: abracket frame adapted to be secured to the main frame of said grindingmachine, said bracket frame having an aperture; a shaft extendingthrough said aperture in said bracket frame and slidable with respectthereto, said shaft carrying an arcuate shoe positioned by said bracketfraMe proximate the periphery of said feedwheel, said shoe carryinglining material for contacting the periphery of said feedwheel infrictional relation; a spring carried by said shaft between said bracketframe and said shoe for biasing said shoe toward said feedwheel to exertforce between said lining and said feedwheel; and means carried by saidshaft on the reverse side of said bracket frame from said spring forselectively locking said shoe in an upraised position relative to saidfeedwheel and freeing said feedwheel from frictional engagement.
 5. Thedevice according to claim 4 wherein said means for selectively lockingsaid shoe in an upraised position comprises cooperating cylindrical cammembers respectively attached to said bracket frame and rotatable onsaid shaft while being longitudinally engageable therewith, said cammembers having a first cooperating position providing the closest axialspacing thereof along said shaft adapting said shaft to carry thearcuate shoe lining material into frictional contact with the saidfeedwheel, and an upraised level position for locating the arcuate shoelining material out of contact with the periphery of said feedwheel. 6.The device according to claim 5 wherein said cam members respectivelycomprise a bushing attached to the said bracket frame and positionedaround the aperture thereof, and a collet rotatable on said shaft, saidcollet being provided with a knurled radial flange means for rotatingthe same, one of said cam members having at least one female dovetail orV-shaped slot adjacent the other cam member, the second cam memberhaving at least one matching V-shaped male dovetail portion adapted tobe received within the female dovetail portion and alternativelyupraisable by means of said radial flange for positioning said dovetailportions out of registry, with the male dovetail portion resting uponthe upper edge of the opposite cam member.
 7. The device according toclaim 6 further including a cap nut and a jam nut secured against oneanother on an upper threaded portion of said shaft on the remote side ofsaid cam members from said bracket frame.
 8. The device according toclaim 4 wherein said bracket frame comprises an angular steel memberhaving a lower portion thereof which is adapted to be secured to themain frame, and carrying said arcuate shoe by an upper portion thereofangularly related to the lower portion.
 9. The device according to claim4 further including an apron extending from said bracket frame insubstantially parallel relation to the said shaft as well as insubstantially perpendicular relation to said bracket frame, said apronextending to a position adjacent said arcuate shoe.
 10. The deviceaccording to claim 9 wherein said apron has an arcuate edge adjacentsaid arcuate shoe, said arcuate edge having a forward contoursubstantially matching that of the arcuate shoe.